Knitting machine

ABSTRACT

There is disclosed a knitting machine each of the knitting needles of which is provided with a hook and a latch capable of pivoting between two positions. In the first position the latch rests against the inside of the hook to close the hook, and in the second position the latch rests against a stop provided on the needle. In the second position, a spur provided on the latch projects beyond the shank of the needle. In order to open and close the hook during knitting, the machine is provided with two pushers for each needle, one pusher being arranged on one side of the needle to contact the spur of the latch to push the latch from the second position to the first position, and the other pusher being arranged on the other side of the needle to contact the latch to push the latch from the first position to the second position.

1J1te States ate 1- Durville 1 Sept. 2, 1975 KNITTING MACHINE [75] Inventor: Gerard Durville, Geneva, Prlmary E) CammerL OuS R'mmdt Switzerland Attorney, Agent, or FtrmKarl F. Ross; Herbert Dubno [73] Assignee: Battelle Memorial Institute, Geneva,

Switzerland 57] ABSTRACT [22] Filed: Apr. 22, 1974 [30] Foreign Application Priority Data Apr. 27, 1973 Switzerland 6078/73 [52] US. Cl 66/13; 66/121 [51] Int. Cl. D0413 35/04 [58] Field of Search 66/13, 62, 63, 104, 107, 66/111,'119, 120122 [56] References Cited UNITED STATES PATENTS 5l,l15 11/1865 Lamb 66/121 61,413 1/1867 Fifield... 1,364,088 l/l92l Fenn 66/13 3,258,938 7/1966 Hofmann 66/119 &

II'IIIIIII'II There is disclosed a knitting machine each of the knitting needles of which is provided with a hook and a latch capable of pivoting between two positions. In the first position the latch rests against the inside of the hook to close the hook, and in the second position the latch rests against a stop provided on the needle. In the second position, a spur provided on the latch projects beyond the shank of the needle. In order to open and close the hook during knitting, the machine is provided with two pushers for each needle, one pusher being arranged on one side of the needle to contact the spur of the latch to push the latch from the second position to the first position, and the other pusher being arranged on the other side of the needle to contact the latch to push the latch from the first position to the second position.

4 Claims, 14 Drawing Figures PATENTED E zisvs sum 3 n5 4 n w oE PATENTEUSEP' 2 91s saw u u; g

FIG. 6

KNITTING MACHINE BACKGROUND OF THE INVENTION The knitting speed of conventional knitting machines is limited by various factors, including above all the deformation tension of the heels of the needles and of the walls of the grooves in which these needles slide. This tension derives from the excessive angles of the needlecontrol cams formed in the frame of the machine. and from the relative speed between the cylinder and the frame. The most widely used hook needle comprises a hook opened and closed by a latch under the effect of the relative axial displacement between the needle and the stitch. In this type of needle, the hook is opened by flattening ofthe latch by the stitch during the ascending stroke of the needle. In order to reclose the hook during the descending stroke of this needle by the same stitch, the length of the ascending stroke of the needle has to be sufficient to disengage the stitch from the latch so that, during the descending course of the needle. the stitch recloses the latch on the hook of the needle and thus moves outside the hook where it drops down on the loop of yarn previously presented to the hook This long stroke required to form the stitch is another factor which limits the speed of knitting machines.

It has already been proposed to obviate these disadvantages by various means.

One of these means comprises forming the needlecontrol cam with constant angles of 53 enabling the length of the knitting cycle to be reduced to a maximum. This results in sudden changes in direction of the needles which give rise to vibration-generating shocks with the result that the rotational speed of the cylinder is limited to a maximum of 1 m/s.

Another means comprises forming the cams with a profile designed so as to produce minimal acceleration and a considerable reduction in the tension in the yarn, and hence in the needle, by virtue of a lowering angle of 60. Tests have shown that the total amount of work required to make the needle descend, at a certain speed of rotation of the cylinder, decreases with the increase in the lowering angle up to coincidence at 60. This improvement in the profile of the dams enables the speed to be increased to 3 m/s and even higher. Nevertheless, there remains a considerable deformation tension of the heel of the needle and of the walls of its groove as a result this lowering angle of60 and of the high speed of rotation of the cylinder.

If the axial stroke of the needle is examined in detail, it is found that only a small part of the overall stroke is useful, the rest of the stroke merely being intended for disengaging the stitch from the latch.

Thus. any increase in the knitting speed is accompanied by a corresponding increase in the deformation placement is produced between the pressure roller and the tip of the needle which tends to twist the needle. In addition. this type of needle complicates the knitting conditions. limiting the production rate to an inadequate level.

In another known needle, the latch is replaced by a piston mounted to slide in the shank of the needle. This type of needle does not lend itself to individual control, with the result that it is fairly widely used in warpknitting machines. There is no weft-knitting machine which uses a needle of this kind known as a tongue or compound needle.

It has also been proposed to use a needle whose oscillating latch is held inside the hook. closure of the needle being controlled by means of a cam which is fixed in relation to the rotating cylinder. In another known solution. opening and closing of the hook by a latch held between the hook and the shank of the needle is obtained by a cam of this kind. Unfortunately. this solution is not really compatible with the increasingly finer gauges used in hosiery because, since the cams which control opening and closing of the hook are fixed in relation to the cylinder, a considerable tangential force is transmitted to the latches by friction, involving a risk of deterioration which is greater, the finer the gauge.

In a more recent solution, the displacement of the needle relative to the cylinder is used to close the hook from behind by means of a latch provided with a closing cam which pushes the latch against the hook during descent of the needle into the cylinder. This latch has an inclined plane designed to generate a couple which tends to draw it back when the yarn is pulled upwards following the ascending movement of the needle.

This system promotes breakage of the yarn because the hook is opened by traction of the yarn on the latch which is no more than a few tenths of a millimeter thick, so that the shearing effect on the yarn is greater. the lower the degree of leverage obtainable in this way. Another disadvantage of this solution is that it is not possible to make opening and closing of the hook coincide with the level to which the stitch is lowered, because. in view of the fact that closure is obtained by means of a cam integral with the latch and by the displacement of the needle relative to the cylinder, the needle must make a certain vertical stroke to produce closure. Now. if it is decided, for example, to make this closure coincide with the lowering level, it is obvious that opening can only be obtained above that level, because the needle has to make a certain vertical stroke to enable it to disengage the cam integral with the latch from the cylinder.

SUMMARY OF THE INVENTION The object of the present invention is to obviate at least some of the disadvantages attending the systems referred to above.

To this end, the invention provides a knitting machine comprising a rotating cylinder equipped with a plurality of vertical needles whose free shank end is curved to form a hook. each needle carrying a latch pivotally connected to the shank in the'plane containing the shank and the hook. the latch being capable of being tilted between two end positions, in the first of which the latch is in contact at its free end with at least part of the inner surface of the hook, whilst in the second the latch rests against a stop associated with the shank of the needle. The latch comprises at least one spur arranged to project beyond the profile of the 5 shank of the corresponding needle when the latch is in second upper position, and vice versa, in order to carry out knitting, and means for controlling tilting of the latch of each needle between the two end positions thereof.

This knitting machine is distinguished by the fact that the aforementioned means are formed, on the one hand, by two pushers arranged on either side of each needle and capable of being displaced along paths contained in at least one plane parallel to the tilting plane of the latch and in the direction of the shank of the needle or in the opposite direction alternatively for each pusher. and on the other hand by a mechanism for entraining the pushers in an alternating movement and with such a stroke that, at least in an axial position of the needle, one of these pushers is capable of contacting the spur of the latch when it is in its second end position, so as to push the latch into the first position, while the other pusher is capable of contacting at least one surface element of the latch occupying, on the latch. a position opposite to that of the spur when the latch is in its first end position, so as to bring the latch into its second position.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawing illustrates very diagrammatically and by Way of example one embodiment and one variant of the knitting machine according to the invention. In the drawing:

FIG. I is a diametral section.

FIGS. 21: and 2/) are partial enlarged views of a needle in the two positions of its latch.

FIG. 3 is a view of this same needle turned through 90 relative to FIGS. 2 and 2b.

FIGS. 4a to 4b are diagrams illustrating the various phases involved in the formation of a stitch.

FIG. is a graph showing the increase in the deformation stresses as a function of the increase in the cam angle.

FIG. 6 is a view similar to FIG. 1 showing a variant.

DESCRIPTION OF THE PREFERRED EMBODIMENT The needle 1 shown in detail in FIGS. 20, 2/: and 3 is a needle equipped with a latch 2. However, and in contrast to conventional latch needles. the latch is held inside the hook 3 formed at the active end of the needle. This latch is accommodated in an elongated opening 4 which extends through the shank of the needle and is pivoted about a pin 5 perpendicular to the plane of the opening 4 and situated near the lower end of that opening. The end of the hook and edge 41! of the open-- ing 4 form the two stops which limit the movement of the latch. As shown in FIG. 2b. the latch 2 has a shoulder 2a which projects towards the rear when the latch is in its opening position. The function of this shoulder 2a will be explained hereinafter.

In addition, as shown in FIGS. 20 and 2b, the tip of the latch 2 is accommodated in the opening 4 in the open position of the hook 3, while the end of the hook 3 is itself accommodated in a recess 2h formed in the tip of the latch. Thus. the yarn is in no danger of being hooked up during the ascent or descent of the needle during formation of the stitch.

The diametral section in FIG. 1 shows the needle I illustrated in FIGS. 2 and 3 mounted in a groove 6 of the cylinder 7 of a weft knitting machine equipped with a lowering plate 8. The cylinder 7 is mounted for rotation inside a frame B about a vertical axis. This knitting machine is illustrated very diagrammatically by only those components required for the understanding of the invention.

The lower end of the needle I is provided with a heel 9 whose front edge is formed with a recess 9a intended to receive the free end of a spring 11. This spring, which in its free state is substantially straight, is subjected to the action of two' cams, namely an ascent cam formed, in this example, by a wheel R, and a descent cam formed, for example, by a fixed lifting surface 10. The wheel R is pivoted freely about a radial pin integral with the frame B. The lowering plate 8 is mounted to slide in a radial plane on the cylinder 7. Each needle is associated with an identical lowering plate. This plate has a heel 8a engaged in a groove 12 integral with the frame B forming the control cam of the plate. The plate 8 is formed with two projections 8/2 and extending laterally in relation to the plane of the plate and arranged on either side of the needle 1.

Whereas the reciprocating movement of the plate is controlled by the cam 12, the displacement of the needle l is controlled by the wheel R and the fixed cam 10 through the spring 11. The wheel R, pivoted freely on a radial axis is entrained by the spring 11 and simultaneously deforms this spring Il whose free end, in contact with the heel 9 of the needle 1, then raises this needle. When the spring leaves the wheel R, it comes into contact with the cam 10 which has a certain falling slope followed by a horizontal section. This cam 10 controls the return of the spring 11 to its initial form under the effect of its own elasticity, while the horizontal section, which follows the inclined section, limits the descent of the needle which determines the size of the stitch.

We shall now refer to FIGS. 4a and 4/1 in order to examine the various phases involved in the operation of this knitting machine. In these Figures, the needle is shown somewhat diagrammatically solely in the interests of simplification. this needle being in reality the same as that illustrated in detail in FIGS. 2 and 3.

FIG. 4a shows hooking of the stitch by displacement of the plate from left to right. At the end of its displacement, the projection 8b comes into contact with the latch 2 and entrains it, thus opening the hook 3. As shown in FIG. 2b. the latch is completely cffaced so that. during ascent of the needle 1, the loop of yarn newly formed slides without meeting any obstacle (FIG. 41)). FIG. 41' illustrates presentation of the yarn to the needle. the yarn being subsequently gathered by the hook 3 of the needle beginning its downward movement. I

At this moment (FIG. 40). while the needle remains fixed. the plate makes a movement from right to left. at the end of which the projection 80 comes into contact with the latch 2 and recloses the hook 3, so that the stitch is able to pass above the hook 3 (FIG. 4f) and to drop down onto the loop (FIG. 4g). When the needle completes its rapid descent. pulling a length of yarn. the plate returns to the right to again begin the cycle while enabling the stitch to be tightened (FIG. 4/2).

It can be seen that. with the knitting machine described here, the amplitude of the movement of the needle is considerably reduced in relation to knitting machines using latched needles whose opening and closing is controlled by the yarn. In fact. this amplitude is strictly limited to the stroke required to disengage the stitch from the hook in order positively ,to close the hook. so that the stitch passes outside the hook and drops down onto the new loop of yarn introduced into the hook.

This reduction in the stroke of the needle affords a number of possibilities both of increasing the productivity of the knitting machine and of refining the gauges. The advantages and disadvantages of the various choices. which can be made by virtue of the reduction in stroke of the needle whose latch'is positively controlled by the plate. will be discussed hereinafter.

One of these possibilities is illustrated in FIG. I, and comprises arming the return spring ll during ascent of the needle. so that the descending movement of the needle is initiated by the spring II and not by a cam, as in conventional knitting machines producing a deformation of the heel of the needle and of the groove in which the needle is mounted. Restoration of the energy of the spring 11 to cause the needle to descend makes it possible to impart to the needle a speed equal to or even higher than the speed produced by a 60 cam without creating any lateral deformation stress.

The substitution of a return spring for the lowering cam is made possible by reduction in the stroke of the needle. because it would be virtually impossible in practice to continue using a spring similar to the spring I] when the longitudinal stroke of the needle becomes greater. i.e. around twice the longitudinal stroke of convention latch needles.

By virtue of the reduction in the stroke of the needle and of the lowering speed. imparted by the spring 11, equal to or higher than the highest speeds hitherto obtained with cams it is possible. for the same number of knitting systems per unit cylinder length. to cause the needle to ascend with a cam of much shallower slope than with an identical knitting machine using conventional latch needles.

Accordingly. since the deformation stresses decrease during ascent because of the reduction in slope and disappear during lowering because of the action of the re turn spring, the speed of the knitting machine can be greatly increased and the gauges can be refined. because it is known that the fineness of the gauges is limited by the lateral stresses applied to the walls of the grooves separating the needles from one another. Now. if these stresses decrease. the thickness of the needles and of the walls can be reduced. thus giving a finer gauge.

if the stroke of the needle I is reduced by about half. it would also be possible to retain the same cam angles which would thus enable the number of knitting systems around the cylinder to be doubled. However, this solution has the disadvantage of accentuating the problem ofspin caused by spiral knitting. In addition, it can be seen from the graph in FIG. 5 that the deformation Stresses of the heel of the needle F K (a) F where K (a) constant as a function of the cam angle a. and F equals force of resistance to displacement. undergo a considerable increase when the angle a of the cam exceeds 40 to to an extent which increases with the resistant force.

Accordingly. it can be deduced from this that it is preferable to increase the rotation speed of the cylinder by reducing the slopes of the cams. rather than to increase the number of knitting systems and retaining the same cam slopes and the same rotational speed.

FIG. 6 shows a variant of FIG. I. The only difference between this variant and the embodiment illustrated in FIG. I is that the plate 8 is mounted in a groove 6' which. forms an angle of about 30 with the horizontal, so that. instead of having a radial movement of the plate perpendicular to the axis of the cylinder 7'. it is inclined. By this inclination in the direction of displacement of the-plate relative to the cylinder, it is possible slightly further to reduce the stroke of theneedle by the relative vertical displacement between the needle and the plate. This variant only slightly modifies the stitchforming cycle described in reference to FIGS. 4a and 4/1. I

Some of the advantages and new possibilities afforded by the knitting machine just described have already been indicated. In conclusion, it can be added that the positive control of the closing latch eliminates the manual or automatic latch-opening operation in the event of the knitted fabric falling.

The control of needle ascent by the springs 11 is another advantage because in the event of wear. it is suffi' cient to replace the worn springs rather than the cylinder itself. which is the case at present.

I claim:

I. A knitting machine comprising:

a rotatable cylinder;

a plurality of vertical needles each of which comprises:

a shank.

a free shank end curved to form a hook.

a latch pivotally mounted on said shank in the plane containing said shank and said hook and capable of being tilted between two end positions in the first of which end positions said latch is in contact with the inner surface of said hook to close said hook.

at stop associated with said shank. said latch'resting against said stop in the second of said two endpositions. and

at least one spur provided on said latch. said spur being arranged to project beyond said shank when said latch is in said second position;

means for controlling alternating axial displacement of said needles to bring each needle from a first lower position to a second upper position, and vice versa, in order to carry out knitting; and

means for controlling tilting of each of said latches between said two end positions, said means comprising: two pushers arranged on either side of each of said needles and capable of being displaced along paths contained in a plane parallel to the tilting plane of said latch and in the direction of said shank or in the opposite direction alternatively for each pusher. and

means for entraining said pushers in an alternating movement and with such a stroke that. at least in an axial position of said needle. one of said pushers is capable of contacting said spur of said latch when said latch is in said second end position so as to push said latch into saif first end position. while the other of said pushers is capable of contacting said latch when said latch is in said first end posi tion so as to push said latch into said second end position.

2. A knitting machine as claimed in claim 1, wherein said means for controlling tilting of each of said latches comprises:

a lowering plate associated with each needle. said two pushers being integral with said plate. and

a guide groove situated in a plane parallel to the tilting plane of said latch. said plate being mounted to slide in said guide groove.

3. A knitting machine as claimed in claim 2, wherein the angle between said guide groove and the vertical path of said needle is an acute angle. whereby said guide groove slopes upwards and. at the same time. diverges from said vertical path.

4. A knitting machine as claimed in claim 2, wherein said means for controlling axial displacement of each sition when said cam ceases to act.

Dedication 3,902,335.-Gerard Durville, Geneva, Switzerland. KNITTING MACHINE. Pa-

tent dated Sept. 2, 1975. Dedication filed Mar. 26, 1984, by the assignee, The Battelle Memorial Institute.

Hereby dedicates to the Peo ple of the United States the entire remaining term of said patent.

[Official Gazette June 12, 1984.] 

1. A knitting machine comprising: a rotatable cylinder; a plUrality of vertical needles each of which comprises: a shank, a free shank end curved to form a hook, a latch pivotally mounted on said shank in the plane containing said shank and said hook and capable of being tilted between two end positions in the first of which end positions said latch is in contact with the inner surface of said hook to close said hook, a stop associated with said shank, said latch resting against said stop in the second of said two end positions, and at least one spur provided on said latch, said spur being arranged to project beyond said shank when said latch is in said second position; means for controlling alternating axial displacement of said needles to bring each needle from a first lower position to a second upper position, and vice versa, in order to carry out knitting; and means for controlling tilting of each of said latches between said two end positions, said means comprising: two pushers arranged on either side of each of said needles and capable of being displaced along paths contained in a plane parallel to the tilting plane of said latch and in the direction of said shank or in the opposite direction alternatively for each pusher, and means for entraining said pushers in an alternating movement and with such a stroke that, at least in an axial position of said needle, one of said pushers is capable of contacting said spur of said latch when said latch is in said second end position so as to push said latch into saif first end position, while the other of said pushers is capable of contacting said latch when said latch is in said first end position so as to push said latch into said second end position.
 2. A knitting machine as claimed in claim 1, wherein said means for controlling tilting of each of said latches comprises: a lowering plate associated with each needle, said two pushers being integral with said plate, and a guide groove situated in a plane parallel to the tilting plane of said latch, said plate being mounted to slide in said guide groove.
 3. A knitting machine as claimed in claim 2, wherein the angle between said guide groove and the vertical path of said needle is an acute angle, whereby said guide groove slopes upwards and, at the same time, diverges from said vertical path.
 4. A knitting machine as claimed in claim 2, wherein said means for controlling axial displacement of each of said needles comprises: a spring, one end of which is integral with said needle and the other end in which is integral with said cylinder, said spring tending to keep said needle in said first lower position, and a cam for displacement of said needle into said second upper position while arming said spring in such a way that said needle returns to said first lower position when said cam ceases to act. 